When to use?
Your test case class should extend
FilterTestCase
whenever you are unit testing:
- Servlet Filters,
- Any java code that uses Filter API objects (
FilterConfig
, ...)As filters only exist in Servlet API 2.3, you must use the Cactus version for Servlet API 2.3 if you wish to write tests for them.Filter unit testing is only available in Cactus 1.2 and above.
Provided Implicit Objects
Cactus automatically initializes the implicit objects for you and they are made available to your
setUp()
,testXXX()
andtearDown()
methods as instance variables of theFilterTestCase
class (and thus as instance variables of your test case class as it extendsFilterTestCase
).You may ask yourself how Cactus initializes these objects. The mechanism is described in the How it works guide.The provided implicit objects are:
request
See
ServletTestCase
request
implicit object for documentation.response
See
ServletTestCase
response
implicit object for documentation.config
Instance variable name config
Class name org.apache.cactus.server.FilterConfigWrapper
, which inherits fromjavax.servlet.FilterConfig
Cactus wraps the original Filter Config for two reasons:
- In order to provide additional methods. For example, it is possible to initialise filter parameters without setting them in
web.xml
, etc...,- So that it can return a wrapped Servlet Context instead of the original one. This is because the Servlet Context is used to perform forwards and includes and we need to pass to these methods the original request and response. As we have wrapped the request, we need to wrap the Servlet Context to pass the original request (and not the wrapped one).
The
config
implicit object will contain all initialisation parameters defined inweb.xml
under the Filter Redirector filter definition.See the javadoc for the
org.apache.cactus.server.FilterConfigWrapper
class for all details. You should also look at the samples provided in the Cactus distribution.Additional methods
Additional methods provided:
setInitParameter()
: sets an initialisation parameter (as if it has been defined in theweb.xml
file),setFilterName()
: sets the Filter name that will be returned bygetFilterName()
(if not set, the Cactus Filter redirector name will be returned).filterChain
Instance variable name filterChain
Class name javax.servlet.FilterChain
Cactus does not wrap the filter chain.
Tips and Tricks
Simulating the next fitler in chain
As you are performing unit testing of your filter, you may wish to simulate the next filter in the filter chain so that you can decide, as part of your unit test, what this other filter returns to your filter under test. Here is how you could do that:
public void testDoFilterOK() throws ServletException, IOException { SampleFilter filter = new SampleFilter(); filter.init(config); [...] FilterChain mockFilterChain = new FilterChain() { public void doFilter(ServletRequest theRequest, ServletResponse theResponse) throws IOException, ServletException { PrintWriter writer = theResponse.getWriter(); writer.print("<p>some content</p>"); writer.close(); } public void init(FilterConfig theConfig) { } public void destroy() { } }; filter.doFilter(request, response, mockFilterChain); [...] }See the samples provided as part of the Cactus distribution.
Sample
This is a very basic sample intended to give you a flavour of Filter unit testing. Check the distribution samples for extensive examples. The filter we are testing here simply adds a header and a footer to the response. The header and footer texts are defined as a parameter defined in
web.xml
.public void testXXX() throws ServletException, IOException { SampleFilter filter = new SampleFilter(); config.setInitParameter("header", "<h1>header</h1>"); config.setInitParameter("footer", "<h1>footer</h1>"); filter.init(config); FilterChain mockFilterChain = new FilterChain() { public void doFilter(ServletRequest theRequest, ServletResponse theResponse) throws IOException, ServletException { PrintWriter writer = theResponse.getWriter(); writer.print("<p>some content</p>"); writer.close(); } public void init(FilterConfig theConfig) { } public void destroy() { } }; filter.doFilter(request, response, mockFilterChain); } public void endXXX(WebResponse theResponse) { assertEquals("<h1>header</h1><p>some content</p><h1>footer</h1>", theResponse.getText()); }